How popular is Erikka?

Erikka is a rare given name for females. Erikka is a unique last name too for both adults and children. (2000 U.S. Census)

Which version is better?

with its source form and related girl names. Popular alternative forms of Erikka (not ranked) are Arica, Arika, Erica(#681 in recent rankings), Ericka, Erika(#728), Eryka, Erykah and Rikki. Other forms, like Elika, are uncommon. Adoption of these relations of Erikka reached its most widespread 25 years ago (usage of 0.9%) and is now much diminished, with versions like Rikki becoming less in vogue. (Top Baby Names, 2015)